<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>01_伸缩容器_伸缩项目</title>
    <style>
        .outer {
            width: 1000px;
            height: 600px;
            background-color: #888;
            /* 将该元素变为了伸缩容器（开启了flex布局） */
            display: flex;
        }
        .inner {
            width: 200px;
            height: 200px;
            background-color: skyblue;
            border: 1px solid black;
            box-sizing: border-box;
        }
        .inner3 {
            display: flex;
            /* font-size: 20px; */
            /* line-height: 2em; */
        }
    </style>
</head>
<body>
    <div class="outer">
        <div class="inner">1</div>
        <div class="inner">2</div>
        <div class="inner inner3">
            <div>a</div>
            <div>b</div>
            <div>c</div>
        </div>
    </div>
</body>
</html>